'\" t
.\"     Title: glPixelStore
.\"    Author: [FIXME: author] [see http://docbook.sf.net/el/author]
.\" Generator: DocBook XSL Stylesheets v1.79.1 <http://docbook.sf.net/>
.\"      Date: 01/03/2018
.\"    Manual: [FIXME: manual]
.\"    Source: [FIXME: source]
.\"  Language: English
.\"
.TH "GLPIXELSTORE" "3G" "01/03/2018" "[FIXME: source]" "[FIXME: manual]"
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.\" disable hyphenation
.nh
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.\" * MAIN CONTENT STARTS HERE *
.\" -----------------------------------------------------------------
.SH "NAME"
glPixelStore \- set pixel storage modes
.SH "C SPECIFICATION"
.HP \w'void\ glPixelStoref('u
.BI "void glPixelStoref(GLenum\ " "pname" ", GLfloat\ " "param" ");"
.HP \w'void\ glPixelStorei('u
.BI "void glPixelStorei(GLenum\ " "pname" ", GLint\ " "param" ");"
.SH "PARAMETERS"
.PP
\fIpname\fR
.RS 4
Specifies the symbolic name of the parameter to be set\&. Six values affect the packing of pixel data into memory:
\fBGL_PACK_SWAP_BYTES\fR,
\fBGL_PACK_LSB_FIRST\fR,
\fBGL_PACK_ROW_LENGTH\fR,
\fBGL_PACK_IMAGE_HEIGHT\fR,
\fBGL_PACK_SKIP_PIXELS\fR,
\fBGL_PACK_SKIP_ROWS\fR,
\fBGL_PACK_SKIP_IMAGES\fR, and
\fBGL_PACK_ALIGNMENT\fR\&. Six more affect the unpacking of pixel data
\fIfrom\fR
memory:
\fBGL_UNPACK_SWAP_BYTES\fR,
\fBGL_UNPACK_LSB_FIRST\fR,
\fBGL_UNPACK_ROW_LENGTH\fR,
\fBGL_UNPACK_IMAGE_HEIGHT\fR,
\fBGL_UNPACK_SKIP_PIXELS\fR,
\fBGL_UNPACK_SKIP_ROWS\fR,
\fBGL_UNPACK_SKIP_IMAGES\fR, and
\fBGL_UNPACK_ALIGNMENT\fR\&.
.RE
.PP
\fIparam\fR
.RS 4
Specifies the value that
\fIpname\fR
is set to\&.
.RE
.SH "DESCRIPTION"
.PP
\fBglPixelStore\fR
sets pixel storage modes that affect the operation of subsequent
\fBglReadPixels\fR()
as well as the unpacking of texture patterns (see
\fBglTexImage1D\fR(),
\fBglTexImage2D\fR(),
\fBglTexImage3D\fR(),
\fBglTexSubImage1D\fR(),
\fBglTexSubImage2D\fR(),
\fBglTexSubImage3D\fR()),
\fBglCompressedTexImage1D\fR(),
\fBglCompressedTexImage2D\fR(),
\fBglCompressedTexImage3D\fR(),
\fBglCompressedTexSubImage1D\fR(),
\fBglCompressedTexSubImage2D\fR()
or
\fBglCompressedTexSubImage1D\fR()\&.
.PP
\fIpname\fR
is a symbolic constant indicating the parameter to be set, and
\fIparam\fR
is the new value\&. Six of the twelve storage parameters affect how pixel data is returned to client memory\&. They are as follows:
.PP
\fBGL_PACK_SWAP_BYTES\fR
.RS 4
If true, byte ordering for multibyte color components, depth components, or stencil indices is reversed\&. That is, if a four\-byte component consists of bytes
b 0,
b 1,
b 2,
b 3, it is stored in memory as
b 3,
b 2,
b 1,
b 0
if
\fBGL_PACK_SWAP_BYTES\fR
is true\&.
\fBGL_PACK_SWAP_BYTES\fR
has no effect on the memory order of components within a pixel, only on the order of bytes within components or indices\&. For example, the three components of a
\fBGL_RGB\fR
format pixel are always stored with red first, green second, and blue third, regardless of the value of
\fBGL_PACK_SWAP_BYTES\fR\&.
.RE
.PP
\fBGL_PACK_LSB_FIRST\fR
.RS 4
If true, bits are ordered within a byte from least significant to most significant; otherwise, the first bit in each byte is the most significant one\&.
.RE
.PP
\fBGL_PACK_ROW_LENGTH\fR
.RS 4
If greater than 0,
\fBGL_PACK_ROW_LENGTH\fR
defines the number of pixels in a row\&. If the first pixel of a row is placed at location
p
in memory, then the location of the first pixel of the next row is obtained by skipping
.sp
k = n ⁢ l a s ⁢ s ⁢ n ⁢ l a ⁢ s >= a s < a
.sp
components or indices, where
n
is the number of components or indices in a pixel,
l
is the number of pixels in a row (\fBGL_PACK_ROW_LENGTH\fR
if it is greater than 0, the
width
argument to the pixel routine otherwise),
a
is the value of
\fBGL_PACK_ALIGNMENT\fR, and
s
is the size, in bytes, of a single component (if
a < s, then it is as if
a = s)\&. In the case of 1\-bit values, the location of the next row is obtained by skipping
.sp
k = 8 ⁢ a ⁢ n ⁢ l 8 ⁢ a
.sp
components or indices\&.
.sp
The word
\fIcomponent\fR
in this description refers to the nonindex values red, green, blue, alpha, and depth\&. Storage format
\fBGL_RGB\fR, for example, has three components per pixel: first red, then green, and finally blue\&.
.RE
.PP
\fBGL_PACK_IMAGE_HEIGHT\fR
.RS 4
If greater than 0,
\fBGL_PACK_IMAGE_HEIGHT\fR
defines the number of pixels in an image three\-dimensional texture volume, where ``image\*(Aq\*(Aq is defined by all pixels sharing the same third dimension index\&. If the first pixel of a row is placed at location
p
in memory, then the location of the first pixel of the next row is obtained by skipping
.sp
k = n ⁢ l ⁢ h a s ⁢ s ⁢ n ⁢ l ⁢ h a ⁢ s >= a s < a
.sp
components or indices, where
n
is the number of components or indices in a pixel,
l
is the number of pixels in a row (\fBGL_PACK_ROW_LENGTH\fR
if it is greater than 0, the
width
argument to
\fBglTexImage3D\fR()
otherwise),
h
is the number of rows in a pixel image (\fBGL_PACK_IMAGE_HEIGHT\fR
if it is greater than 0, the
height
argument to the
\fBglTexImage3D\fR()
routine otherwise),
a
is the value of
\fBGL_PACK_ALIGNMENT\fR, and
s
is the size, in bytes, of a single component (if
a < s, then it is as if
a = s)\&.
.sp
The word
\fIcomponent\fR
in this description refers to the nonindex values red, green, blue, alpha, and depth\&. Storage format
\fBGL_RGB\fR, for example, has three components per pixel: first red, then green, and finally blue\&.
.RE
.PP
\fBGL_PACK_SKIP_PIXELS\fR, \fBGL_PACK_SKIP_ROWS\fR, and \fBGL_PACK_SKIP_IMAGES\fR
.RS 4
These values are provided as a convenience to the programmer; they provide no functionality that cannot be duplicated simply by incrementing the pointer passed to
\fBglReadPixels\fR()\&. Setting
\fBGL_PACK_SKIP_PIXELS\fR
to
i
is equivalent to incrementing the pointer by
i ⁢ n
components or indices, where
n
is the number of components or indices in each pixel\&. Setting
\fBGL_PACK_SKIP_ROWS\fR
to
j
is equivalent to incrementing the pointer by
j ⁢ m
components or indices, where
m
is the number of components or indices per row, as just computed in the
\fBGL_PACK_ROW_LENGTH\fR
section\&. Setting
\fBGL_PACK_SKIP_IMAGES\fR
to
k
is equivalent to incrementing the pointer by
k ⁢ p, where
p
is the number of components or indices per image, as computed in the
\fBGL_PACK_IMAGE_HEIGHT\fR
section\&.
.RE
.PP
\fBGL_PACK_ALIGNMENT\fR
.RS 4
Specifies the alignment requirements for the start of each pixel row in memory\&. The allowable values are 1 (byte\-alignment), 2 (rows aligned to even\-numbered bytes), 4 (word\-alignment), and 8 (rows start on double\-word boundaries)\&.
.RE
.PP
The other six of the twelve storage parameters affect how pixel data is read from client memory\&. These values are significant for
\fBglTexImage1D\fR(),
\fBglTexImage2D\fR(),
\fBglTexImage3D\fR(),
\fBglTexSubImage1D\fR(),
\fBglTexSubImage2D\fR(), and
\fBglTexSubImage3D\fR()
.PP
They are as follows:
.PP
\fBGL_UNPACK_SWAP_BYTES\fR
.RS 4
If true, byte ordering for multibyte color components, depth components, or stencil indices is reversed\&. That is, if a four\-byte component consists of bytes
b 0,
b 1,
b 2,
b 3, it is taken from memory as
b 3,
b 2,
b 1,
b 0
if
\fBGL_UNPACK_SWAP_BYTES\fR
is true\&.
\fBGL_UNPACK_SWAP_BYTES\fR
has no effect on the memory order of components within a pixel, only on the order of bytes within components or indices\&. For example, the three components of a
\fBGL_RGB\fR
format pixel are always stored with red first, green second, and blue third, regardless of the value of
\fBGL_UNPACK_SWAP_BYTES\fR\&.
.RE
.PP
\fBGL_UNPACK_LSB_FIRST\fR
.RS 4
If true, bits are ordered within a byte from least significant to most significant; otherwise, the first bit in each byte is the most significant one\&.
.RE
.PP
\fBGL_UNPACK_ROW_LENGTH\fR
.RS 4
If greater than 0,
\fBGL_UNPACK_ROW_LENGTH\fR
defines the number of pixels in a row\&. If the first pixel of a row is placed at location
p
in memory, then the location of the first pixel of the next row is obtained by skipping
.sp
k = n ⁢ l a s ⁢ s ⁢ n ⁢ l a ⁢ s >= a s < a
.sp
components or indices, where
n
is the number of components or indices in a pixel,
l
is the number of pixels in a row (\fBGL_UNPACK_ROW_LENGTH\fR
if it is greater than 0, the
width
argument to the pixel routine otherwise),
a
is the value of
\fBGL_UNPACK_ALIGNMENT\fR, and
s
is the size, in bytes, of a single component (if
a < s, then it is as if
a = s)\&. In the case of 1\-bit values, the location of the next row is obtained by skipping
.sp
k = 8 ⁢ a ⁢ n ⁢ l 8 ⁢ a
.sp
components or indices\&.
.sp
The word
\fIcomponent\fR
in this description refers to the nonindex values red, green, blue, alpha, and depth\&. Storage format
\fBGL_RGB\fR, for example, has three components per pixel: first red, then green, and finally blue\&.
.RE
.PP
\fBGL_UNPACK_IMAGE_HEIGHT\fR
.RS 4
If greater than 0,
\fBGL_UNPACK_IMAGE_HEIGHT\fR
defines the number of pixels in an image of a three\-dimensional texture volume\&. Where ``image\*(Aq\*(Aq is defined by all pixel sharing the same third dimension index\&. If the first pixel of a row is placed at location
p
in memory, then the location of the first pixel of the next row is obtained by skipping
.sp
k = n ⁢ l ⁢ h a s ⁢ s ⁢ n ⁢ l ⁢ h a ⁢ s >= a s < a
.sp
components or indices, where
n
is the number of components or indices in a pixel,
l
is the number of pixels in a row (\fBGL_UNPACK_ROW_LENGTH\fR
if it is greater than 0, the
width
argument to
\fBglTexImage3D\fR()
otherwise),
h
is the number of rows in an image (\fBGL_UNPACK_IMAGE_HEIGHT\fR
if it is greater than 0, the
height
argument to
\fBglTexImage3D\fR()
otherwise),
a
is the value of
\fBGL_UNPACK_ALIGNMENT\fR, and
s
is the size, in bytes, of a single component (if
a < s, then it is as if
a = s)\&.
.sp
The word
\fIcomponent\fR
in this description refers to the nonindex values red, green, blue, alpha, and depth\&. Storage format
\fBGL_RGB\fR, for example, has three components per pixel: first red, then green, and finally blue\&.
.RE
.PP
\fBGL_UNPACK_SKIP_PIXELS\fR and \fBGL_UNPACK_SKIP_ROWS\fR
.RS 4
These values are provided as a convenience to the programmer; they provide no functionality that cannot be duplicated by incrementing the pointer passed to
\fBglTexImage1D\fR(),
\fBglTexImage2D\fR(),
\fBglTexSubImage1D\fR()
or
\fBglTexSubImage2D\fR()\&. Setting
\fBGL_UNPACK_SKIP_PIXELS\fR
to
i
is equivalent to incrementing the pointer by
i ⁢ n
components or indices, where
n
is the number of components or indices in each pixel\&. Setting
\fBGL_UNPACK_SKIP_ROWS\fR
to
j
is equivalent to incrementing the pointer by
j ⁢ k
components or indices, where
k
is the number of components or indices per row, as just computed in the
\fBGL_UNPACK_ROW_LENGTH\fR
section\&.
.RE
.PP
\fBGL_UNPACK_ALIGNMENT\fR
.RS 4
Specifies the alignment requirements for the start of each pixel row in memory\&. The allowable values are 1 (byte\-alignment), 2 (rows aligned to even\-numbered bytes), 4 (word\-alignment), and 8 (rows start on double\-word boundaries)\&.
.RE
.PP
The following table gives the type, initial value, and range of valid values for each storage parameter that can be set with
\fBglPixelStore\fR\&.
.PP
.TS
allbox tab(:);
lB cB cB cB.
T{
\fB \fR\fB\fIpname\fR\fR\fB \fR
T}:T{
\fB Type \fR
T}:T{
\fB Initial Value \fR
T}:T{
\fB Valid Range \fR
T}
.T&
l c c c
l c c c
l c c c
l c c c
l c c c
l c c c
l c c c
l c c c
l c c c
l c c c
l c c c
l c c c
l c c c
l c c c
l c c c
l c c c.
T{
\fBGL_PACK_SWAP_BYTES\fR
T}:T{
boolean
T}:T{
false
T}:T{
true or false
T}
T{
\fBGL_PACK_LSB_FIRST\fR
T}:T{
boolean
T}:T{
false
T}:T{
true or false
T}
T{
\fBGL_PACK_ROW_LENGTH\fR
T}:T{
integer
T}:T{
0
T}:T{
0
                                ∞
T}
T{
\fBGL_PACK_IMAGE_HEIGHT\fR
T}:T{
integer
T}:T{
0
T}:T{
0
                                ∞
T}
T{
\fBGL_PACK_SKIP_ROWS\fR
T}:T{
integer
T}:T{
0
T}:T{
0
                                ∞
T}
T{
\fBGL_PACK_SKIP_PIXELS\fR
T}:T{
integer
T}:T{
0
T}:T{
0
                                ∞
T}
T{
\fBGL_PACK_SKIP_IMAGES\fR
T}:T{
integer
T}:T{
0
T}:T{
0
                                ∞
T}
T{
\fBGL_PACK_ALIGNMENT\fR
T}:T{
integer
T}:T{
4
T}:T{
1, 2, 4, or 8
T}
T{
\fBGL_UNPACK_SWAP_BYTES\fR
T}:T{
boolean
T}:T{
false
T}:T{
true or false
T}
T{
\fBGL_UNPACK_LSB_FIRST\fR
T}:T{
boolean
T}:T{
false
T}:T{
true or false
T}
T{
\fBGL_UNPACK_ROW_LENGTH\fR
T}:T{
integer
T}:T{
0
T}:T{
0
                                ∞
T}
T{
\fBGL_UNPACK_IMAGE_HEIGHT\fR
T}:T{
integer
T}:T{
0
T}:T{
0
                                ∞
T}
T{
\fBGL_UNPACK_SKIP_ROWS\fR
T}:T{
integer
T}:T{
0
T}:T{
0
                                ∞
T}
T{
\fBGL_UNPACK_SKIP_PIXELS\fR
T}:T{
integer
T}:T{
0
T}:T{
0
                                ∞
T}
T{
\fBGL_UNPACK_SKIP_IMAGES\fR
T}:T{
integer
T}:T{
0
T}:T{
0
                                ∞
T}
T{
\fBGL_UNPACK_ALIGNMENT\fR
T}:T{
integer
T}:T{
4
T}:T{
1, 2, 4, or 8
T}
.TE
.sp 1
.PP
\fBglPixelStoref\fR
can be used to set any pixel store parameter\&. If the parameter type is boolean, then if
\fIparam\fR
is 0, the parameter is false; otherwise it is set to true\&. If
\fIpname\fR
is a integer type parameter,
\fIparam\fR
is rounded to the nearest integer\&.
.PP
Likewise,
\fBglPixelStorei\fR
can also be used to set any of the pixel store parameters\&. Boolean parameters are set to false if
\fIparam\fR
is 0 and true otherwise\&.
.SH "ERRORS"
.PP
\fBGL_INVALID_ENUM\fR
is generated if
\fIpname\fR
is not an accepted value\&.
.PP
\fBGL_INVALID_VALUE\fR
is generated if a negative row length, pixel skip, or row skip value is specified, or if alignment is specified as other than 1, 2, 4, or 8\&.
.SH "ASSOCIATED GETS"
.PP
\fBglGet\fR()
with argument
\fBGL_PACK_SWAP_BYTES\fR
.PP
\fBglGet\fR()
with argument
\fBGL_PACK_LSB_FIRST\fR
.PP
\fBglGet\fR()
with argument
\fBGL_PACK_ROW_LENGTH\fR
.PP
\fBglGet\fR()
with argument
\fBGL_PACK_IMAGE_HEIGHT\fR
.PP
\fBglGet\fR()
with argument
\fBGL_PACK_SKIP_ROWS\fR
.PP
\fBglGet\fR()
with argument
\fBGL_PACK_SKIP_PIXELS\fR
.PP
\fBglGet\fR()
with argument
\fBGL_PACK_SKIP_IMAGES\fR
.PP
\fBglGet\fR()
with argument
\fBGL_PACK_ALIGNMENT\fR
.PP
\fBglGet\fR()
with argument
\fBGL_UNPACK_SWAP_BYTES\fR
.PP
\fBglGet\fR()
with argument
\fBGL_UNPACK_LSB_FIRST\fR
.PP
\fBglGet\fR()
with argument
\fBGL_UNPACK_ROW_LENGTH\fR
.PP
\fBglGet\fR()
with argument
\fBGL_UNPACK_IMAGE_HEIGHT\fR
.PP
\fBglGet\fR()
with argument
\fBGL_UNPACK_SKIP_ROWS\fR
.PP
\fBglGet\fR()
with argument
\fBGL_UNPACK_SKIP_PIXELS\fR
.PP
\fBglGet\fR()
with argument
\fBGL_UNPACK_SKIP_IMAGES\fR
.PP
\fBglGet\fR()
with argument
\fBGL_UNPACK_ALIGNMENT\fR
.SH "VERSION SUPPORT"
.TS
allbox tab(:);
lB cB s s s s s s s s s s s
lB cB cB cB cB cB cB cB cB cB cB cB cB.
T{

T}:T{
\fBOpenGL Version\fR
T}
T{
\fBFunction / Feature Name\fR
T}:T{
\fB2\&.0\fR
T}:T{
\fB2\&.1\fR
T}:T{
\fB3\&.0\fR
T}:T{
\fB3\&.1\fR
T}:T{
\fB3\&.2\fR
T}:T{
\fB3\&.3\fR
T}:T{
\fB4\&.0\fR
T}:T{
\fB4\&.1\fR
T}:T{
\fB4\&.2\fR
T}:T{
\fB4\&.3\fR
T}:T{
\fB4\&.4\fR
T}:T{
\fB4\&.5\fR
T}
.T&
l c c c c c c c c c c c c
l c c c c c c c c c c c c.
T{
\fBglPixelStoref\fR
T}:T{
✔
T}:T{
✔
T}:T{
✔
T}:T{
✔
T}:T{
✔
T}:T{
✔
T}:T{
✔
T}:T{
✔
T}:T{
✔
T}:T{
✔
T}:T{
✔
T}:T{
✔
T}
T{
\fBglPixelStorei\fR
T}:T{
✔
T}:T{
✔
T}:T{
✔
T}:T{
✔
T}:T{
✔
T}:T{
✔
T}:T{
✔
T}:T{
✔
T}:T{
✔
T}:T{
✔
T}:T{
✔
T}:T{
✔
T}
.TE
.sp 1
.SH "SEE ALSO"
.PP
\fBglReadPixels\fR(),
\fBglTexImage1D\fR(),
\fBglTexImage2D\fR(),
\fBglTexImage3D\fR(),
\fBglTexSubImage1D\fR(),
\fBglTexSubImage2D\fR(),
\fBglTexSubImage3D\fR(),
\fBglCompressedTexImage1D\fR(),
\fBglCompressedTexImage2D\fR(),
\fBglCompressedTexImage3D\fR(),
\fBglCompressedTexSubImage1D\fR(),
\fBglCompressedTexSubImage2D\fR(),
\fBglCompressedTexSubImage1D\fR()\&.
.SH "COPYRIGHT"
.PP
Copyright
\(co
1991\-2006 Silicon Graphics, Inc\&. Copyright
\(co
2010\-2014 Khronos Group\&. This document is licensed under the SGI Free Software B License\&. For details, see
\m[blue]\fBhttp://oss\&.sgi\&.com/projects/FreeB/\fR\m[]\&.
.SH "COPYRIGHT"
.br
Copyright \(co 1991-2006 Silicon Graphics, Inc.
.br
Copyright \(co 2010-2014 Khronos Group
.br